chore (extensions/open-virtual-networking) : Move `kubernetes-model-ovn` to `extensions/open-virtual-networking`
As discussed in
https://github.com/fabric8io/kubernetes-client/pull/5724#issuecomment-1907630802
it's better to have Open Virtual Networking types available as a
separate extension.
Move previously added `kubernetes-model-generator/kubernetes-model-ovn`
to `extensions/open-virtual-networking/model-v1`
Signed-off-by: Rohan Kumar <rohaan@redhat.com>